Electric discharge vessel



July 28, 1942- R.ISCHARFNAGEL ET'AL 2,290,999

ELECTRIC DISCHARGE VESSEL Filed April 5, 1940 invemor Patented July 28,1942 UNITED STATES PATENT OFFICE ELECTRIC DISCHARGE VESSELAktiengesellschaft, many, a company Berlin- Tempelhof,

Ger-

Application April 3, 1940, Serial No. 327,646 In Germany March 30, 19392 Claims.

This invention relates to electric discharge vessels of the kind havinga glas seal fitted to the bulb which is preferably made of metal inorder to serve as anode in well known manner.

It has been proposed to increase the thermal loading capacity of thesedevices by raising the thermal inertia effective in the ne ghbourhood ofthe glass seal. The mean best adapted for th s purpose is a heatacclnnulating body arranged in close proximity to the glass seal. Suchbody may be of a suitable metal. Metal, however, although very suitablein this regard, increases the detrimental capacities and thus impair theelectric properties of the discharge vessels.

According to the invention the heat accumulating body is constituted bythe insulating carrier of the electrode system. This carrier pref"erably consists of ceramic material. According to a further feature ofthe invention such ceramic carrier is made of sintered corundum.

In the accompanying drawing Fig. l. is a somewhat diagrammatic sectionalview showing embodiment of the invention; Fig. 2 is a partly broken awayand sectionalized View of this embodiment; and Fig. 3 represents asection taken in the plane of line AA of Fig. 1.

The discharge vessel here illustrated by way of example ha a metallicbulb I which is conically enlarged at 2, The electrode system E issupported by leads 3 which are carried by means of a block 4 of a denseceramic material. This block is pressed into the bulb so as to snuglycontact with the wall thereof. To the outer end face of block 4 a disc 5is fixed by means of vitreous material that forms a glass disc 1 andreaches through perforations 5 of the disc 5. Disc 5 is of a porousceramic material.

The disc 5 may be fixed to block 4 by a sintering proces to which aseparate glazing frit or some other binding agent of low vapor pressureis subjected during the process of producing the glass disc I.

The disc 5, however, need not at all be united with block 4. Theprocedure in this case may be as follows: In the first place, theassembly 3, 5, I is manufactured. Then the block 4 is inserted over theleads 3, whereupon the electrode system E is mounted on the leads.Finally, the

supporting assembly 3, 4, 5, I for the system E is sealed into the bulbI.

Alternatively, the disc 5 may be omitted and the block 4 may be in itsturn porous. In this case block 4 may also be provided with longitudinalbores or with recesses formed in close adjacency in the outer end facethereof. In this way vitreous material applied to this end face willenter such groove or recesses when melted down, being transformedthereby into a glass disc equivalent to the disc 1 shown in the draw mg.

The block 4 is a solid body which is easy to manufacture. Owing to thefact that this block intimately contacts with the bulb I the heat fromthis bulb is directly transferred to it. The heat conductivity of theceramic material of which the block is made is such that the heat received from bulb I is quite uniformly distributed in the block, whichtherefore in its turn and with the aid of disc 5 acts to transfer theheat to the glass disc 1 uniformly to all parts thereof.

Block 4 may consist of magnesium silicate, such as the material knownunder the names Frequenta or Calite. Preferably, however, sinteredcorundum is suitable for this purpose. In fact, the heat conductivity ofthis material is ten times that of the two other said materials, theheat received by block 4 thus being distributed most uniformly over theglas disc I so as to prevent strains arising therein. In this way theglass disc 1 will be able to stand temperatures of 600* to 700 C. duringlong periods of operation.

In distinction from prior arrangements having metal arranged as a heataccumulating means, in the case of the novel device the inherentdielectric losses and capacity conditions are not affected todisadvantage since the heat accumulating means 4, 5 is of insulatingmaterial so as not to diminish in electric relation the distance betweenthe leads 3 and the metal wall of bulb I.

What is claimed is:

1. A discharge vessel comprising a metal bulb having an opening therein,heat accumulating means blocking said opening comprising a carrier bodyof dense ceramic material snugly fitted to the wall of said bulb and adisc of porous ceramic material, means for mounting an electrode systemon said body, and a glass seal covering said mean and sealed to saidbulb, said disc being located between said body and said seal.

2. A discharge vessel according to claim 1 wherein said disc is fixed tosaid body by a binding agent of low vapor pressure, said agent beingsintered to said body and said disc.

RUDOLF SCHARFNAGEL. FELIX HERRIGER.

